1. Field of the Invention
The instant disclosure relates to an injection system, and more particularly to an injection system applied to a die casting machine.
2. Description of Related Art
In a die casting machine, an injection plunger is used to inject a molten metal into a cavity of a die by an injection plunger. The quality of the cast product greatly depends upon the injection speed of the molten metal and the casting pressure (injection pressure). Therefore, it is necessary to suitable control the speed of movement (injection speed) and pressure of the injection cylinder driving the injection plunger. That is, the injection speed and the casting pressure (injection pressure) are controlled in accordance with the state of filling the molten metal between the casting cycles to realize the optimal injection operation.
For example, in a predetermined zone after the start of injection, the injection plunger is made to move by a low injection speed so that the molten metal in the injection sleeve does not enter air. Next, when the front end of the molten metal reaches the inlet of the cavity, the injection speed is switched from low speed to high speed to make the injection plunger move by a high injection speed so as to complete the filling of the molten metal into the cavity before the molten metal cools and solidifies. After the molten metal finishes being filled into the cavity, the casting pressure (injection pressure) is rapidly increased and the molten metal is allowed to solidify while applying pressure to the molten metal in the cavity.